What do you know about the Snowball Earth?

Consider this an informal poll – does the phrase “Snowball Earth” mean anything to you?
This is more aimed at those amongst my readership who are not professional rock-hounds. Also, “no” is an entirely acceptable answer: it’s the one I’ve got from virtually everyone I’ve tried to explain my new research to thus far – hence the question, since I thought that at some level it had gained a little traction in the public consciousness. If I was wrong, that’s an important thing to know.

The idea that earth was completely covered with ice in the past. That is the extent of my understanding though, I’ve no idea when such a thing occured nor how it affected the earth and its inhabitants. I would be interested in learning about your research. not a professional rock hound, partnered to an amateur rock hound

Was a long time ago? 400+ million years? So continents were different, no land life, all of that stuff. I don’t get the almost killed all life meme? Wasn’t it a little too early to have any idea about life survival? I kind of get this confused with the 250 MYA Permian events. Nothing like me messing up slightly by more time than from now to before the dinosaurs… just a little error.
Loved “Trilobyte”, “Earth” and “Life” by Fortey, “Extinction” by Erwin even more for its look at the “experimental” aspects of geology, i.e. coming up with ideas then looking for evidence with different tools, and searching for layers of rock to fit. Have degree in physics but no formal geology background.

I know of it – the theory that the Earth was once completely covered in ice before the Cambrian explosion.
I’m a software engineer, but I read the encyclopedia for fun. I’ve never heard it come up in conversation or even anywhere else online since. I think it’s pretty safe to say that it’s not a very well-known hypothesis among non-geeks.

Yes. I don’t know the details of the hypothesis, but I have read that it’s somewhat controversial in that there’s evidence that during snowball earth period there was a narrow temperate zone near the equator.

Yes, read about it from Scientific American, I think. Here in Scandinavia the traces of the previous ice age are an essential part of the landscape (you might say “the whole landscape”), so I have some interest in the hypothesis.
I’m a middle-aged computer engineer with a major in applied physics (but not geo-anything).

Yes it does the earth used to be colder than a grant reviewer’s heart. This was a long time ago, before anything interesting was happening on earth (like the burial of magnetic pigs).
Oh , and I’m either a biologist or a statistician, whichever one is going to confuse you the most.

Yes, courtesy of books, magazines, documentaries, and blogs like this one. No professional standing in any discipline; just interested in science.
I’m very hazy on when and for how long, but I believe that the idea is that an uncongenial (life-wise) distribution of the land masses kicked off runaway freezing; more ice, more solar energy reflected rather than absorbed->still more ice, lather, rinse, repeat. Eventually, enough CO2 built up (volcanism) to reverse the trend.

I saw the documentary a while back, either on Science Channel or Discovery. Quite liked it, because of how well it demonstrated how science worked. Someone has an idea, shows the evidence that supports it (and why it doesn’t really fit the existing ideas), then every one from every genre (physics, geology, chemistry, and biology) try to shoot it down with reasons why it wouldn’t work, and (here’s the important bit…) they come up with experiments to show why their counter might not be right.
At every point, they came up with a test case to show what they would expect to see, yay or nay. Even if Snowball Earth is really not factual (as in, some test case finally flunks it), the documentary is tremendous in showing that aspect of science. It’s not just “I’m right your wrong”, it’s “I think I’m right, go try to shoot holes in it and lets see.”
I wish that documentary was shown in every science class in America, just to get the “lone mad scientist” and “just-so stories” bullshit out of the denialist (and creationist) talking points.

Yes, but not much. The Earth was once completely or nearly completely covered with ice, way back when. Before metazoans?
I would normally look up a vaguely familiar term before posting, but that would probably negate the purpose of this survey. I am a computer geek, interested in science goings on, but not a scientist.
I believe it is a respectable theory, but not universally held.

Oh pick me, me me me !! oh me !! me me me me me !!!
Well I’ve seen on the BBC that it’s also called the Cryogenian which is really cool as a name, it sounds like the entire planet was dipped into liquid nitrogen. The proof of it, the voice said, is that there are chunky bits of rocks embedded into compressed chewy sand just like you find where glaciers have been. And meringues (or moraines) and things. And this means that there were glaciers all over the planet. It was all triggered by a nasty thing called “life”, which started pumping oxygen all around 3 bubblion years ago. Life again eh?! Tell me about life !
But then lately I’ve read that there might have been multiple cryogenians. Wasn’t there a 70’s scifi film with Paul Newman like that ?
Living in fear of the big ice cream van,
EspressoFrog.

Yes. I’ve heard of the theory. Extreme glaciation at one point in Earth’s history, continental glaciation approaching the equator. Volcanic eruptions and C02 increase were the primary factors in getting the Earth out of the deep freeze.

Yes – business modeling engineer.
Proposed, though still largely controversial, period in early Earth development in which extensive glaciation dominated. In the most extreme models, the Earth was entirely glaciated during this period. Banded iron deposits are the primary physical evidence; exit mechanism is unclear (lava flat-style volcanism is popularly proposed).
There are also some claims to a previous Snowball Earth era in the Hadrean that was broken by the development of methanogenic life, but that’s even less established and not usually what the term refers to.

Yes, but not much. Geo degree 1988, the idea was around, but NOT widely accepted at that point. Best coverage I’ve read was in Life on a Young Planet by Andrew Knoll (excellent, if you haven’t read it). Hadn’t realized until then that it was becoming accepted rather than fringe. That was maybe 4 1/2 years ago.

Yes, developmental biology and human genetics. But I don’t recall much about it, or where I first read about it. Looking forward to tracking down the book Lockwood suggested so I can brush up on the subject!

Runaway glaciation during the Precambrian. Original theory said the Earth was totally covered with ice and life almost extinguished. A severe round of vulcanism (perhaps triggered by the weight of the ice sheets) began the deicing. I believe the theory has been modified lately with a few more almosts and nearlys.

Most off a Discovery show, but I have head it mentioned briefly – this is the theory that the Earth froze once (generally froze completely – ice covered everything). I think recent investigations of climate data or creatures, I forget, suggest that the Earth has never been completely frozen over. I haven’t looked into it too much.

Yes, although I was only ever aware of it as a fringe theory. Last heard it on the aforementioned Discover Channel show (an episode of Naked Science), although I didn’t watch the episode. – Bachelor’s in physics, researching cognitive science, but with a serious personal interest in climate change. Only formal exposure to geosciences would be the basic first-year rocks-for-jocks course and an introduction to geophysics, neither of which touched on this.

Yes. I have been aware of this idea for a couple of years after a program on the Discovery channel.
More recently, I have seen a show suggesting that one cause of the glaciation (which may or may not have completely covered the planet) was the distribution of the continents.
I am a degreed geologist who now teaches high school earth/space science.

Yep. Intelligent layman with an interest in biology and evolutionary history. From what I understand, it’s a fairly controversial theory, no? I don’t have sufficient knowledge to have an opinion, though.

I’ve heard of it too, probably from reading New Scientist and other similar magazines. My idea of what it means is similar to what other people have mentioned previously, and I’m pretty vague on the details (completely frozen over, or a warm-ish equator?).
Geek with a general science interest – presumably like many other readers of ScienceBlogs – would be the obligatory who-i-am mention.

I love my readers. Thanks everyone – this is much more the sort of thing I was expecting, although I realise the ScienceBlogs audience is a little self-selecting.
And don’t worry, there will be Snowball Earth blogging.

Yes, from the documentary, ‘How the Earth Was Made’. I was watching it again last night actually. I am a chemist but I know very little earth science/geology and look forward to Snowball Earth blogging.